Miniature plug-in fuses are well known in the automotive industry. Such fuses commonly have a fuse assembly formed as a unitary metal stamping. The fuse assembly comprises a pair of parallel, blade-like terminals and a fuse element that extends between the terminals. (The term "fuse element" is used in this specification to identify the component of a fuse which actually overhears and opens in response to an overload current). A plastic housing is molded about the fuse assembly with the terminals extending from the housing. The housing plugs into a complementary socket adapted to retain the housing and electrically engage the terminals. Once plugged in, only one face of the housing is exposed and the fuse element cannot be visually checked for continuity even if the housing is formed of transparent plastic. Conductive contacts are thus provided at the exposed housing face to a conventional continuity checker to be used. Such fuses and methods of manufacturing them are described in U.S. Pat. Nos. 3,909,767; 3,962,782; 4,040,175 and 4,056,884, all to Avinash and Williamson.
Such fuses are difficult to replace when burnt out. A special tool is normally used to grip and remove the fuse. An automobile user will not normally have such a tool. Also, he may not have a replacement fuse conveniently available. Although a mechanic using a continuity checker may be able to quickly isolate a defective fuse among multiple fuses, an automobile user is unlikely to have such a device and may have difficulty determining which fuse is most likely defective. In its various aspects, the present invention plug-in fuse devices that eliminate such problems.